HCA2 activation in Pemphigoid Diseases - therapeutic effect and mode of action

在P8中，我们研究了富马酸二甲酯(DMF)治疗类天疱疮(PDs)的药理学基础。DMF已经在肠道内转化为富马酸单甲酯(MMF)，它是G蛋白偶联受体HCA2(Gpr109a)的激动剂。事实上，我们发现证据表明，HCA2在大疱性类天疱疮(BP)样大疱性获得性表皮松解症(EBA)小鼠模型中介导了最近描述的口服DMF的保护作用。因此，DMF改善了雌性Hcar2+/+小鼠的类天疱疮样皮肤损害，但对Hcar2-/-动物没有影响。出乎意料的是，经赋形剂处理的雌性Hcar2-/-动物部分免受EBA的影响，这表明HCA2具有Janus-Face功能：如果被内源性激动剂激活，则有害，而对外源应用的药物有利。在第二个FP中，我们将调查这种矛盾功能的原因，以牢固地确立HCA2作为治疗PDS的药物靶点。首先，我们将仔细研究内源性Hca2激活剂的作用，包括丁酸盐、β-羟丁酸盐和烟酸，通过改变饮食。由于饮食相关代谢物对帕金森病病理的潜在影响可能对患者护理具有重要影响，我们将通过在小鼠和人类患者身上进行代谢组学研究来寻找HCA2激活的间接证据。其次，我们将定义介导内源性和药理学HCA2激活剂效应的细胞类型(S)。对这个问题进行最先进的研究是可能的，使用我们已经产生的一种新的小鼠系，其中loxP位点被插入到Hcar2基因座中。如果靶细胞没有完全重叠，我们的目标是将药理学HCA2的激活限制在身体部分，在那里有益的效果占主导地位。第三，我们将讨论内源性和药理学HCA2激活剂的动力学特征，这可能解释它们不同的作用。为了接近这一点，我们将确定BP患者口服该药物后的血药浓度动力学曲线，该患者将参加由CRU财团发起并由欧盟委员会资助的BP DMF临床试验，并将通过皮下植入可调泵注入化合物在小鼠身上建立模型。

In P8, we have investigated the pharmacological basis of using dimethyl fumarate (DMF) in the treatment of pemphigoid diseases (PDs). Already in the gut, DMF is converted into monomethyl fumarate (MMF), an agonist of the G protein coupled receptor HCA2 (GPR109A). Indeed, we found evidence that HCA2 mediates the recently described protective effect of oral DMF in a mouse model of bullous pemphigoid (BP)-like epidermolysis bullosa acquisita (EBA). Thus, DMF ameliorated pemphigoid disease-like skin lesions in female Hcar2+/+ mice, but not in Hcar2-/- animals. Unexpectedly, vehicle-treated female Hcar2-/- animals were partially protected from EBA suggesting a Janus-faced function of HCA2: detrimental if activated by endogenous agonists and beneficial in response to exogenously applied drugs. In the 2nd FP, we will investigate the reason of this ambivalent function to firmly establish HCA2 as a drug target for the treatment of PDs. First, we will scrutinize the role of endogenous HCA2 activators, including butyrate, β-hydroxybutyrate, and nicotinic acid, by modifying the diet. As a potential effect of diet-related metabolites on PD pathology could have important ramifications for patient care, we will search for indirect evidence of HCA2 activation by performing metabolomic studies in mice and human patients. Second, we will define the cell type(s) that mediate effects of endogenous and pharmacological HCA2 activators. A state-of-the-art investigation of this question is possible using a novel mouse line, we have generated, in which loxP sites have been inserted into the Hcar2 locus. If there is no complete overlap in the target cells, we will aim to limit pharmacological HCA2 activation to the body compartment, in which beneficial effects prevail. Third, we will address the kinetic profiles of endogenous and pharmacological HCA2 activators that may explain their distinct actions. To approach this point, we will determine the kinetic profile of the drug’s plasma concentrations after oral administration in BP patients, who will be part of the clinical trial on DMF in BP, initiated by the CRU consortium and funded by the EU commission, and will model it in mice by infusing the compound through a subcutaneously implanted adjustable pump.